When an aircraft is travelling on the ground, the aircraft is subject to one or more forces, which will cause the aircraft to change heading or veer. In order to maintain a desired heading and to compensate for veering, it is necessary for a pilot or co-pilot to make regular use of steering mechanisms such as nose wheel steering. Veering may be caused by external factors such as cross winds or gusts, uneven runway or taxiway cambers and atmospheric conditions. Veering may also be caused by the setup of the aircraft, such as uneven engine thrusts, steering system misalignment, steering servo drift or uneven tyre pressures.
Maintaining or correcting the heading of an aircraft by means of the tiller, hand wheels or the rudder and thus leads to additional workloads for the pilot or co-pilot.